Install gtest dependency in workflow

Author: sgunes-wirepas

Diff for: .github/workflows/c-cpp.yml

@@ -21,8 +21,8 @@ jobs:
     - name: make proto example
       run: make
       working-directory: example/linux/proto-api
-    - name: install libpaho-mqtt
-      run: sudo apt install libpaho-mqtt-dev
+    - name: install needed packages libpaho-mqtt
+      run: sudo apt-get update && apt-get install -y libpaho-mqtt-dev libgtest-dev
     - name: make gateway example
       run: make
       working-directory: example/linux/gw-example